The fighting literally hangs from cliffs and rocky promontories. White smoke rises from a village across a deep gorge. The screeching whistle of mortar fire echoes in the expansive valley as troops target militants in a village five miles away. Cobra helicopter gunships buzz overhead. Two weeks into its ambitious ground assault on the Pakistani Taliban's heartlands, the Pakistani army has edged its way east and says it is poised to make fresh gains against the Central Asian and Taliban fighters who are hunkered down in the Kaniguram Valley, faintly visible in the distance.

It was the most that journalists have been able to see of the fighting, which is perhaps Pakistan's sternest test against the Pakistani Taliban and their al-Qaeda allies in South Waziristan. Accompanied by the army, a group of local and foreign journalists were taken by helicopter to the fringes of the fighting on Thursday, where they got a rare glimpse of areas that are notorious for being sanctuaries for al-Qaeda and Pakistan's most dangerous terrorists in recent years.

After three days of what it called fierce fighting, the army seized control of Shelwasti village, on a rocky, largely barren hilltop in the Sherwangai Valley. "We moved in as a battalion at night to take the terrorists by surprise," says Lieut. Colonel Inam Rasheed Tarar. Mud-walled homes divided by narrow alleyways served as the militants' hideouts. A wide-ranging reserve of weaponry, documents, laptop computers and plans for explosive devices put out on display by the army revealed an apparently sophisticated and well-resourced enemy that may have once sheltered leading members of al-Qaeda. (See pictures of the aftermath of suicide bomb attacks in Islamabad.)

Alongside carefully arrayed mortar shells, short-range artillery equipment and a range of rifles is a pile of papers and documents. Among them are plans showing how to assemble an "impact grenade" and a "time delay" grenade. Other pieces of paper, handwritten in Arabic, apparently lay out instructions on how to rig another explosive device. Also among the documents are two European passports that purportedly belong to fugitive al-Qaeda members who are linked to the 9/11 attacks and the 2004 Madrid bombings. (Read about how Pakistan's army is finally getting serious about its internal enemies.)

Most prominent is a German passport that appears to have belonged to Said Bahaji, 34, a member of the Hamburg cell that orchestrated the 9/11 attacks who was close to its ringleader, Mohamed Atta. The passport was apparently issued in Hamburg to Bahaji, the son of Moroccan and German parents, on Aug. 3, 2001. A Pakistani tourist visa valid for 90 days that appears inside the passport was stamped the following day. An entry stamp from Karachi dated Sept. 4, 2001, suggests that Bahaji landed in the Pakistani port city just a week before the attacks on New York and Washington. There was no sign of further travel in the passport.

It was not possible to verify the authenticity of the passport, number L8642163, or determine whether its apparent holder had been in the area, had been killed or had abandoned it there years ago. But the details in the passport closely matched those available from an Interpol-U.N. Security Council Special Notice. The passport number only differs by one digit, and the photographs are clearly of the same person.

Another passport the army claimed it recovered, and seen by reporters on the visit, belonged to Raquel Burgos Garcia, also 34, a Spaniard who had converted to Islam and later joined al-Qaeda as a low-level operative. The Spanish passport, number P099823, did not bear any Pakistani stamps. Her passport was also issued just weeks before the 9/11 attacks, on Aug. 1, 2001.

According to a Moroccan student card purportedly belonging to Garcia that was displayed with her passport, she is the wife of Amer Azizi, a Moroccan terrorist suspect linked to the 2004 Madrid bombings. Garcia's passport bore no traces of travel to Pakistan but did have stamps showing repeated travel to Morocco, her apparent husband's country. There was also a used travel visa to Iran, where Azizi is reported to have fled at one point. And there was an Indian visit visa, but it did not appear to have been used for travel.

If genuine, the passports would confirm what the U.S. has been saying all along: that Pakistan's wild borderlands have served as a sanctuary for global jihadis who may be plotting fresh attacks on the West. Bahaji served as a "senior al-Qaeda propagandist," says a senior U.S. counterterrorism official. Soon after the 9/11 attacks, it was widely reported that members of the Hamburg cell had their first known meeting at Bahaji's 1999 wedding in a Hamburg mosque.

The emergence of the passports came the same day that U.S. Secretary of State Hillary Clinton vented frustration at Pakistan's failure to capture al-Qaeda members who are suspected to be sheltering in these very tribal areas. "I find it hard to believe that nobody in your government knows where they are and couldn't get them if they really wanted to," Clinton told Pakistani journalists at a meeting in Lahore. No Pakistani officials reacted to her remarks.

Foreign fighters aligned with al-Qaeda make up a large component of the fighters that the army is taking on in South Waziristan. The military's chief spokesman, Major General Athar Abbas, said that some 1,500 Central Asian fighters, mainly Uzbeks, were among the 5,000 to 8,000 fighters that the offensive was targeting.

On Friday, the army said it had mounted the ridges around Sara Rogha, one of the three towns  along with Makeen and Laddha  that form a "triangle of militancy." After three earlier offensives that faltered, the army said it is demonstrating hardened resolve that will not let up. The last operation was halted, said Abbas, because of "two vulnerabilities": the failure to secure the army's fort at Laddha and to evacuate the civilian population in the area. In the South Waziristan areas under army control on Thursday, no civilians were in sight in the rugged, sparsely populated valley. More than 155,000 civilians left as the army moved in over the past fortnight, adding to the numbers of people that have fled in years past.

Since the late 19th century, when Mullah Powindah  the first religiously inspired fighter from the Mehsud tribe  harried British troops, South Waziristan has troubled modern armies. Pakistan's ongoing wave of vicious suicide attacks has brutally demonstrated the need to eliminate the militants who are based here. But the fighting is only going to get tougher. And when the army does manage to clear the area, as it expects to do within three months, holding on to the territory may prove even harder.

By choking off the main roads, troop commanders on the ground are confident that they are bleeding the militants dry and protecting against their flight to other areas. But a visit to Kotkai  the hometown of Taliban leaders Hakimullah Mehsud and Waliur Rehman, which was cleared by the army last week  was not possible due to the continuing threat of rocket fire from militants nearby. There is no clear idea of either of the Taliban commanders' whereabouts, though there have been unconfirmed reports of Mehsud hiding atop Preghal in Badr Valley, South Waziristan's highest peak. Some observers speculate that he may have shifted into North Waziristan, beyond the scope of the offensive, a claim that the army dismisses.